1. Field of the Invention
The present invention relates to an applicator including a writing instrument, such as a marking pen and a felt pen, and a corrector of written letters or figures.
2. Description of Related Art
Construction of an applicator, which is mainly in use for writing letters, characters or figures, underlining, or putting in colors to outline pictures, is disclosed in U.S. Pat. No. 5,615,963, to Kobayashi, or Japanese Laid-open Patent Application 2000-79787.
The applicator disclosed by Kobayashi is equipped with a penpoint tip, a valve and a liquid reservoir containing liquid ink. When the valve is opened by compressing the penpoint tip against a surface, ink from the reservoir permeates into the penpoit tip and then exudes from the tip.
In the applicator disclosed in Japanese Laid-open Patent Application 2000-79787, a xe2x80x9cshaft tubexe2x80x9d or a hollow main body accommodates an ink-occluding body, which occludes ink. A penpoint tip attached to an end of the main body exudes ink.
Either of the applicators described above is composed of a main body and a penpoint tip. Liquid to be applied, such as ink, is reserved in the main body and the penpoint tip is attached to an end of the main body via a tip holder.
Most of tip holders of prior art applicators are made of commonly used synthetic resin, which is flammable. In most cases, liquid in the reservoir contains flammable solvent such as alcohol and ether.
When a prior art applicator is kept uncapped, whether the applicator is being used or whether it has been left uncapped, the penpoint tip of the applicator is kept exposed to the outer air. Therefore, the solvent exudes and vaporizes from the tip and thus flammable vapor spreads into the surrounding atmosphere, incurring danger of taking fire. A child might set fire to the penpoint tip by mischief.
Once the vapor that has spreaded from the penpoint tip catches fire, not only the solvent occluded in the tip burns, but also the tip itself ignites as the resin constituting the tip reaches flammable temperature, generating more heat. Then the tip holder ignites and finally the liquid in the main body burns, thus generating much more heat. If a curtain or a carpet in a room might catch fire, it might be more dangerous.
In Japan, flame retardancy evaluating test is formulated by means of Japanese Industrial Standards JIS A1321. Recently ACMI Standard to evaluate flame retardancy is also applied in Japan. However, to my knowledge, no applicator having a penpoint tip or a tip holder made of resin has met the requirement of the JIS or the ACMI Standard.
The present invention is directed to solve the problem pointed out above, and has for its object to provide an inexpensive and convenient applicator having less combustibility and improved safety.
An aspect of the invention to solve the problem is an applicator comprising;
a main body containing flammable liquid to be applied;
a tip holder; and
a penpoint tip attached to the main body via the tip holder:
wherein the tip holder is made of flame-retardant resin.
The resin may be synthetic resin or natural resin.
Possibility of ignition of the penpoint tip cannot be avoided insofar as a flammable solvent is contained in the ink. However, even if the penpoint tip of the applicator of the invention has ignited, fire cannot spread over the tip holder, as the tip holder is made of a flame-retardant resin. Therefore, fire on the penpoint tip of the applicator cannot spread to the ink in the main body.
Preferably the flame-retardant resin has an oxygen index more than 30 percent.
The term xe2x80x9coxygen indexxe2x80x9d is an index representing flame-retardant or noncombustible degree and identified by Japanese Industrial Standards JIS K7201. More specifically, an xe2x80x9coxygen indexxe2x80x9d is identified as xe2x80x9ca percentage of a minimum density of oxygen necessary for maintaining combustion of a tested material for a predetermined timexe2x80x9d. Consequently, if the oxygen index of the material exceeds 21 percent, combustion of the material in normal air hardly continues. The flame retardancy of the material increases with the oxygen index.
The inventor has found that the oxygen index of the flame-retardant resin constituting the tip holder of an applicator containing normal flammable ink should be more than 30 percent to meet the requirement of JIS and ACMI.
Based on this point, the above-described aspect of the invention prevents fire on the penpoint tip from spreading to the ink in the main body.
Preferably the flame-retardant resin consists essentially of:
(a) at least one selected from the group consisting of polybutylene terephthalate, polyolefin, polycarbonate and ABS resin (acrylonitrilebutadiene-styrene resin) and
(b) inorganic substance.
ABS resin may be made by any known method, for example, by graft copolymerization or by polymer-blending.
More specifically, it is preferred that inorganic metal compound, such as antimony oxide, or glass fiber is contained in the flame-retardant resin. A flame-retardant resin containing inorganic substance such as monoammonium phosphate, boric acid, and metal fiber may be utilized. A flame-retardant resin containing ceramics such as zirconia and boron nitride as inorganic substance may also be utilized.
Most of publicly known highly flame-retardant resins are expensive or difficult to mold because of their high melting point. The inventor made tests to select resins suitable for the material of the tip holder among a lot of frame-retardant resins. The invention is based on these tests. As most of the inks contained in non-aqueous marking pens etc. contain alcohol and/or ether as a solvent, which has a relatively moderate combustibility, the above-described resin, which is obtained by mixing inorganic substance such as inorganic metal compound and/or glass fiber with at least one selected from the group consisting of polybutylene terephthalate, polyolefin, polycarbonate and ABS resin, shows a flame retardancy sufficient for practical use. Additionally, the above-described flame-retardant resin is easy to mold.
Preferably, the flame-retardant resin contains inorganic substance more than 15 percent by weight of the flame-retardant resin.
More preferably, the flame-retardant resin contains inorganic metal compound and/or glass fiber more than 15 percent by weight of the flame-retardant resin.
The flame-retardant resin may include a flame-retardant agent. The flame-retardant agent may be at least one selected from the group consisting of a chloride flame-retardant agent, a bromide flame-retardant agent, a phosphate flame-retardant agent, and an inorganic flame-retardant agent.
Though composition of liquid contained in the main body may be selected at user""s option, alcohol, ether, ketone, or mixture thereof may be employed as solvent. Noncombustible solvent such as water may be contained in the liquid.
The penpoint tip may also be made of flammable material.
More specifically, the penpoint tip may be made essentially of acrylic resin or polyacetal.
The main body may also be made of flammable material.
Preferably the penpoint tip is in close contact with the tip holder.
In another aspect of the invention, the applicator includes:
a main body containing flammable liquid to be applied;
a tip holder; and
a penpoint tip attached to the main body via the tip holder:
wherein the main body and the tip are made of flammable material;
wherein the liquid contains alcohol, ether and/or ketone as solvent;
wherein the tip holder is made of a composite material consisting essentially of:
(a) a resin and
(b) inorganic metal compound and/or glass fiber more than 15 percent by weight of the composite material.
In a still other aspect of the invention, the applicator includes:
a main body containing flammable liquid to be applied;
a tip holder; and
a penpoint tip attached to the main body via the tip holder:
wherein the liquid contains alcohol, ether and/or ketone as solvent;
wherein the tip holder is made of a composite material consisting essentially of:
(a) at least one selected from the group consisting of polybutylene terephthalate, polyolefin, polycarbonate and ABS resin and
(b) inorganic substance; and
wherein an oxygen index of the resin is more than 30 percent.
As the penpoint tip of the applicator of this aspect is made of flame-retardant resin that has an oxygen index more than 30 percent, fire on the penpoint tip cannot spread over the tip holder. Especially the solvent of the contained liquid is one compound selected from the group consisting of alcohols, ethers, and ketones or mixture of compounds selected from the group consisting of alcohols, ethers, and ketones, heat generating from combustion of the solvent is not enough to burn the tip holder compulsorily or to melt the tip holder. Additionally, the tip holder is easy to mold.